CKEditor - Real-time collaborative future-ready rich text editor
TinyMCE - TinyMCE is a content editor that functions as a plug-in for Wordpress websites.
Aloha Editor - Aloha Editor is an HTML5 WYSIWYG Editor that gives you a total new experience when editing.
Summernote - Summernote is a JavaScript library that helps users create WYSIWYG editors online.
WYMeditor - WYMeditor is a web-based WYSIWYM (What You See Is What You Mean) XHTML editor (not WYSIWYG).
Editor.js - A block-styled editor with clean JSON output